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In experimental design, the response variable is central to the ultimate goal of an experiment. It represents the effect or outcome measured to understand the impact of various factors.

For instance, in an experiment conducted by a printing company, the response variable is the 'binding strength' of books. This variable is pivotal as it indicates the quality and durability of the book binding, directly affecting customer satisfaction and product longevity. Measuring the response variable accurately is crucial, as it is the basis on which the efficacy of different glues will be compared.

It's worth noting that a well-defined response variable should be measurable, consistent, and appropriate to the objective of the study. In the case of binding strength, this could be quantified using appropriate measurement techniques that are sensitive enough to detect differences between glues.

Conversely, the explanatory variable, also known as the independent variable, is manipulated within the experimental design to explore its effect on the response variable.

In our printing company scenario, the type of glue represents the explanatory variable. By using three different types of glue across various samples, the experimenter can observe how the binding strength varies with each kind. Since the explanatory variable is under the control of the experimenter, its role is to determine the different conditions under which the experiment is carried out.

Selecting an explanatory variable that accurately reflects the purpose of the study is vital. It should be varied in a controlled manner so that the relationship with the response variable can be clearly identified and understood.

The accurate interpretation of an experiment's results is often complicated by the presence of extraneous variables. These are variables other than the explanatory variable that may affect the response variable, adding unwanted variability to the experiment and potentially confounding the results.

In our book binding example, the number of pages and the type of book binding (paperback or hardback) are extraneous variables. They are not the focus of the experiment but could influence the binding strength and thus must be carefully managed.

It's important to control or account for extraneous variables where possible, for example, by keeping them constant across all experimental conditions or using statistical methods to adjust for their impact. Failure to manage extraneous variables can lead to incorrect conclusions about the relationship between explanatory and response variables.

A key aspect of any experimental design involves the precise measurement of the outcome of interest. In the context of our glue-based experiment, binding strength measurement is a technical challenge that requires meticulous attention. The metric for success in this experiment is how well the glue holds the pages together, with 'binding strength' as a quantifiable indicator of performance.

Different methods could be employed to measure binding strength, such as tensile testing, which involves applying pressure until the binding fails. The choice of measurement technique can greatly influence the reliability of the results. Accuracy, repeatability, and representativeness of the actual conditions under which the books will be used are critical to the measurement process.

The measurement method must be standardized to allow for fair comparison between the different glues. Hence, developing a well-conceived protocol for binding strength measurement is a fundamental and often complex step in the experimental design.